Transcutaneous electric nerve stimulator (TENS) units are used by persons to block pain transmitted by the nervous system. These devices generate electrical pulses having a peak output voltage, pulse width and pulse rate. The pulses are transmitted to electrodes which are positioned on a person's body depending on the location of the pain. The amplitude of the pulses is adjustable to a level that will minimize the pain. Different people have different sensitivity thresholds to pain and stimulation.
Testing of the TENS units is important to determine whether the units are functioning properly in order to separate the person's subjective pain problems from possible difficulties with the units themselves. Such testing has not been routinely undertaken heretofor because of the lack of properly designed testing equipment.